COGNITIVE ERGONOMICS

BY,Dept. Of Ergonomics

N.I.T.I.E.,MUMBAIDERG-2013 Batch

Why Consider Human Factors?

• Enhance efficiency (productivity)• Ensure safety• Assure tasks are within human capability• Improve human performance• Gain market acceptance• Reduce costs (economic, legal, social)

Human in the Human factors:

• Humans are involved in all aspects of technology– Designers– Users (operators)– Maintenance personnel

• The problems of technology failure:• machine failure• human error• interaction of humans and machines (system

error)

Physical Ergonomics Vs Cognitive Ergonomics

• Physical ergonomics focuses on our bodies• Cognitive ergonomics is interested in what

goes on in our brains:– the way our senses perceive information– the way in which we understand and interpret it– what determines the decisions we make

COGNITIVE ERGONOMICS

• Studies cognition in work settings, in order to optimize human well-being and system performance

• Focuses on the fit between human cognitive abilities and limitations and the machine, task, environment

Goals of Cognitive Function

Aims at enhancing performance

of cognitive tasks by:

User-centered design of human-

machine interaction and human-

computer interaction

Design of information technology

systems that support cognitive

tasks (e.g., cognitive artifacts)

Development of training programs

Work redesign to manage

cognitive workload and increase

human reliability

• The way people perceive and act has direct implications

for the design of the artefacts and environment that they

use

Mind is as comfortable at work as the body

• If physical surroundings reflect and support their natural

cognitive tendencies,

Less errors

performance & productivity -positive boost

SELECTIVE ATTENTION

Limited ability to transmit information

Allocation of attention

If not selectively attend to individual aspects of the tasks, performance – impossible

Failures to notice & attend to displays, warnings - human errors n accidents

Factors for attention failures :

1)Attentional capacity & demands

2)Expectations

3)Stimulus salience

Attention-al capacity:

Most fundamental constraint

Attention is single, undifferentiated but limited

resource(kahneman ,1973)

Use sensory channel that have spare capacity

Eg : primary task -vision (driving) –more use of auditory displays

Task related work load :

Extremely high or low workload – less attentive

Expectations:

• Less likely to notice unexpected stimuli

• Perceptual confusions

• see or hear what they want to ….

• Solution in such situations is to increase salience

of important information

Stimulus Sailence:

• Lights - brighter

• Tones & sounds - louder

• Movement & changes in intensity

eg: use of flashing lights, freq modulated tones, waving

flags

So as to capture the attention during task

performance

EXAMPLES OF COGNITIVE IN APPLICATION:

• Designing a software interface to be "easy to use“

• Designing a sign so that the majority of people will understand and act in the intended manner

• Designing an airplane cockpit or nuclear power plant control system so that the operators will not make catastrophic errors

Cognitive Ergonomics Introduction:

• Cognitive ergonomics studies cognition in work settings• In order to optimize human well-being and system

performance• An emerging branch of ergonomics that places

particular emphasis on the analysis of cognitive processes

• Cognitive processes:– Diagnosis– Decision making– Planning

Broad Definition of Cognitive :

• The configuration of equipment and furniture in a hospital operating room to maximize team performance and minimize errors of perception, attention and judgment

• The design of a commercial jet’s cockpit to correspond to the crew’s natural tendencies in perception, memory, and decision making

Cont……

• The creation of an office environment to minimize distractions and maximize productivity and performance

• The arrangement of a classroom to maximize information exchange, knowledge creation, and acquisition

MAN-MACHINE SYSTEM

HUMAN-MACHINE SYSTEM

• Sensory

• Cognitive

• Motor

• Display

• Processor

• Control

• Human • Machine

•In

terf

ace

Models Of Cognitive Ergonomics:

• Recent models of cognitive ergonomics involve three dimensions:

• Usefulness• usability • acceptance

Usability:

• The degree to which a product or service is easy to use, easy to learn, and optimized for efficiency

• ISO 9241-11 “Guidance on Usability”• Extent to which a product can be used by

specified users to achieve specified goals with effectiveness, efficiency and satisfaction

Cont…..

• Effectiveness - Accuracy and completeness with which users achieve specified goals

• Efficiency - Resources expanded in relation to the accuracy and completeness with which users achieve goals

• Satisfaction - Freedom from discomfort, and positive attitudes towards the user of the product

• Related fields• Human-computer interaction • NeuroErgonomics • Supervisory control

Neuro- Ergonomics

• Using Brain Function to Enhance Human Performance in Complex Systems

• - The scientific study of brain mechanisms and psychological and physical functions of humans in relation to technology, work, and environments

• “N`euro-ergonomics involves the

• examination of the neural bases

• of perceptual, cognitive and motor

• functions in relation to real-world

• applications as mediated through Machines.”

Adaptive Human-MachineSystems

Design In Human Equipments With Ideal Cognition Controls

• Why this Course is Not Human Factors Design • Design of Safe and

Automated Cockpit in Boeing 777

• Design of a safe and

useful infusion pump

Because Minds and Brains are “Situated”—in a Body and Environment with artefacts and Tools—Hence Cognitive Engineering

Cognition System:

FITTING THE TASK FOR MAN

Activities in Human memory• PERCEPTION:

• complex sensory processes

• primary images containing all information about the concrete features of objects (visual, acoustic, etc)

• MEMORY:

• ability to remember, recognize and recall

• information is encoded, stored and retrieved.

• active: structuring, constructive and creative psychic mechanism.

• THOUGHT: the process of information processing in working memory

MEMORY

POOR ERGONOMICS IN DESIGN AND PERCEPTION

• Driving at night in Santa Cruse takes a little bit of extra attention. The street lights emit yellow light instead of the more typical bluish white. Actually, I think the yellow street lights use less electricity too. The problem is that sometimes it is difficult to tell whether a light is a yellow street light or a yellow traffic light. The photo shows a view down a Santa Cruse street with an arrow pointing out two green traffic lights

CAR DRIVING IN MUMBAI

• In contrast, the same photo shows the same view with yellow traffic lights. Notice how the yellow traffic lights look similar to the street lights. Imagine you are driving along at night and don't notice that the yellow lights ahead are yellow traffic lights. You might be very surprised when they turned red. I wonder if this causes traffic accidents?

Why doesn't this marker cap fit?

• Why weren't the kids putting the caps on their colored markers after using them? I noticed that after unsuccessful attempts to put on the caps, they just left the markers uncovered. Sometimes even I had difficulty putting on the marker caps. A closer examination of a marker cap revealed the problem: both ends of the cap look the same. At a glance it looks like the marker can be inserted into either end of the cap. Actually the marker will fit into only one end of the cap. The incorrect end of the cap does not fit either end of the marker. The correct end of the cap does have a slightly raised ring around it, a feature which you may learn to identify. Initially, however, this subtle clue does not help you get the cap on correctly.

IDEAL DESIGN CAP

• The incorrect end should not appear as if the marker could be inserted. This could be accomplished most naturally by blocking the opening on the incorrect end like these other marker caps.

Objectives in Cognition Ergonomics:

• shorten the time to accomplish tasks• reduce the number of mistakes made• reduce learning time• improve people’s satisfaction with a system

• Cognition is the processing of environmental information acting on the environment

• Any available system that processes information in its environment to act upon it could be called “Cognitive System” and performs “cognitive work”.

Knowledge Interpretation

• Procedural : information corresponds to knowledge of how to do something• Declarative : information corresponds to knowledge of facts

Levels of task performance ( given by Rasmussens):

Different forms of information - used at each level of performance

Skill based: automatic processing of signals , no conscious control –seen in various sensory

motor tasks like tracking a moving object with your eyes or steering a vehicle

• Rule based :sequential cuing of responses by consciously perceived cues or signs, eg: when a

stop light changes from red to green, people decide to go.

• Knowledge based:

more laborious

clear formation of plans for attaining some goal

involves meaningful manipulation of symbols

• Products and environment - designed to provide signals & cues - easily perceived, easily discriminated and valid indicators of conditions, functions, hazards & misuses.

• Information transmissionDepends on both :Information sent & its effect on receiver

eg: A speedometer - display the current speed of a vehicle -very high, look at it , slow down - you realize you are speeding

HCI

Human-Computer Interaction HCI involves the study, planning, and design of the interaction between people

(users) and computers.

• Supporting knowledge on both the computer and the human

• Computer side - techniques in computer graphics operating systems,

programming languages and development environments - relevant

• Human side - communication theory, graphic and industrial design disciplines,

linguistics, social sciences, cognitive psychology and human factors such as

computer user satisfaction - relevant

• Interaction occurs at the user interface which includes both hardware and

software

Cont….• Collaboration to perform a task, to do Cognitive Work

The flow of information between the human and computer - loop of interaction

including:

• Task environment: The conditions and goals set upon the user

• Machine environment: The environment that the computer is connected to, e.g. a laptop

in a college student's dorm room.

• Areas of the interface: Non-overlapping & overlapping areas• Input flow: begins in the task environment, user has some task that requires computer

use

• Output: originates in the machine environment

• Feedback: Loops through the interface that evaluate, moderate, and confirm processes as they pass from the human through the interface to the computer and back

2. Intervention areasDesign• The process that happens from the conceptualization of the

artefact until when it is used by the people for whom it is intended

• 2 main aspects in system design(Carroll, 1991).

“The process" of design itself

How people devise a new system, what are the factors involved in making decisions

Technological innovation

Ergonomists "proactively" supply ideas and

empirical data for the design of future artefacts improving human

performance and public acceptance of new technologies.• The concept of "user-centered design" developed in 1980´s in the

design of technologies (Norman, 1986)

• Aims at describing the human being interacting with the system from the viewpoint of cognitive science

• Eg : Essential elements of user centered design of a web site - visibility, accessibility, legibility and language

• Visibility constructs a mental model of the document

• Accessibility To find information quickly and easily throughout the document, regardless of its length. Navigational elements, search functions, table of contents, clearly labeled sections, page

numbers, color-coding etc.) Chunking - useful strategy

Legibility• Easy to read useful font style

• Ornamental fonts and text in all capital letters ,italics and bolding - helpful when used correctly.

• High figure-ground contrast between text and background increases legibility

• Dark text against a light background is most legible.

Cont….

• The allocation of functions to both humans and artefacts

• The design of the interface through which humans and artefacts communicate while collaborating in performing the task

Adaptive Functions

• Human and artefacts interact to perform a task by performing cognitive functions

• Therefore, the design of interaction is to describe how these cognitive functions are allocated to humans and artefacts

• “Adaptive function allocation” to mean that functions could be re-allocated through the interaction

Functional Analysis:

• The first cognitive level: sensory-motor– interaction is described from the point of view of the

characteristics of the human sensory and motor systems• Interaction occurs when the output of the device,

be this visual, auditory, or of any other physical type, is captured by human sensory receivers

• Human behavior would be processed through the motor system, and it is essential that the device has the necessary input systems to receive it in the appropriate way

Design phase

• Cognitive ergonomics is promoting "user-centered design", in the sense that users are integrated in the design process as early as possible

• “ User centered design addresses early and continuous focus on users, empirical measurements, interactive design and multidisciplinary design teams

Evaluation Phase:

• User centered design involves iterative design, so that evaluation is conducted at every stages of development.

Human-System Interface Technology

Human-Machine: Hardware Ergonomics

Human-Environment: Environmental Ergonomics

Human-Software: Cognitive Ergonomics

Human-Job: Work Design Ergonomics

Human-Work System: Macro-ergonomics

Mental workload and stress

• Whenever a person is faced with a task - implement some cognitive resources leading to a variety of functional states that are known “mental workload”, “fatigue", "stress” etc - work performance

• Mental and physical health

• Development of specialized human-computer interfaces intend to reduce the demands for cognitive resources.

• Sometimes tool developed to assist people impose additional

burden - excessive stress and loss of situation awareness

WHAT IS MENTAL WORK LOAD ? Mental workload is the portion of operator’s limited mental

capacities actually required to perform a particular task.

Mental reserves are the difference between capacity required and capacity available.

Mental effort is the voluntary matching of mental capacities with that needed for task success.

Increase in Mental Workload often precedes Performance Failure.

THE NEED TO MEASURE WORK LOAD

Primary Task Techniques

• Measures the Performance Outcome as • a function of Primary Task Demand

How well are you Flying? How well are you Driving?

Primary Load TechniquesAs task load increases, the additional demands on mental

capacities result in a degradation in performance

• Advantages of This Measure:

• Workload reflected directly by performance outcome.

• Non-invasive and non-interfering.

• Tracks changes in workload dynamically. (i.e., as performance proceeds)

• Uncontaminated by memory issues

• Disadvantage of This Measure:

• Only sensitive to changes in workload at the limits of mental capacity

• If operators can compensate for increased workload by increasing their • Effort, the primary task measure is insensitive

• Mental Workload not distinguished from performance outcome

Cont…

• What About Failure?

• Most of the time we’d like to know about Mental Workload to know how much is too much?

• Primary Task measures do not tell us this.

• So, - they fail to be informative just at the time they are needed most!

Bad Ergonomic Design :

Example: Tractor Forwarding Units, South African Forestry IndustryOriginal Unit: Poor operator seating and visibility

Re-designed With User In Mind :

Tractor-Trailer Forwarding Units

South African Forestry Industry

Redesigned Unit: Good operator

seating and visibility

Workload and Vigilance

• Vigilance is a Long-Standing Problem.

• Sources of Performance Influence Include:

1. Event Rate

2. Signal Salience

3. Stress/Workload/Fatigue

4. Glare, Noise, Temperature, Vibration, TOD,

Drug Effects etc

5. Memory Load

6. Successive vs. Simultaneous Comparisons

7. Feedback

8. Hit vs. Miss vs. FA KR/KP

9. Individual Differences

10. Introversion/Extraversion, Age, Sex,

Expertise

WHY DO ERRORS HAPPEN ?

• Person approach– Blame the individual for forgetfulness, inattention,

weakness – Countermeasures: write another procedure, disciplinary

measures, threat of litigation, retrain, blame, shame. • System approach

– Multiple faults that occur together in an unanticipated interaction create chain of events in which faults grow and evolve.

– Countermeasures: based on assumption that though we cannot change the human condition, we can change the conditions under which humans work (e.g., system defenses

What is a Poorly Designed System?

• One that – Does not match the needs of a human being or

task– Does not take into account human limitations

(perception, memory, anthropometrics).

Ergonomics and Workflow

Systems Approach:

• Two principles:– Same set of circumstances can provoke similar

errors, regardless of the people involved.– Safety is seriously impeded if an organization does

not seek out and remove the error provoking properties within the system at large.

Human Error • What is an error?

– Failure of a planned action to be completed as intended (error of execution) or use of a wrong plan to achieve an aim (error of planning).

• Active failures (sharp end) – Occur at the level of the frontline operator– Effects are felt almost immediately.

• Latent conditions (blunt end) – Tend to be removed from the direct operator control– Result in two kinds of adverse events:

• Error provoking conditions within the local workplace (e.g., time pressure, understaffing, inadequate equipment, fatigue, inexperience)

• Create long-lasting holes in defenses (e.g., design deficiencies, untrustworthy alarms, unworkable procedures

• Example:

– Active error: The pilot crashed the plane.

– Latent error: A previously undiscovered design malfunction caused the plane to roll unexpectedly in a way the pilot could not control and the plane crashed.

Reason’s Swiss Cheese Model

ERROR MANAGEMENT :• Limiting errors• Creating more error-tolerance• High reliability organizations capable of…

– Performing exacting tasks under pressure – Carrying out activities with low incident rates– Good organizational design and management– Organizational commitment to safety– High levels of redundancy– Strong organizational culture– Converting occasional setbacks into enhanced resilience of the

system.

Safety and accident investigation

• Errors - not caused by irresponsible behaviour

or defective mental functioning

May be a consequence of not having taken into

account ,how a person perceives, attends,

remember, makes decisions, communicates

and acts in a particularly designed work system

• Investigating the causes of human errors by analyzing the characteristics of human information processing

• classification of errors according to the level of processing involved in the behavior

• Jens Rasmussen (1983) - 3 types of errors depending on the level and degree of cognitive control involved in the erroneous behavior

• Errors based on skills: familiar with the task, actions – over learned as a low-

level pre-programmed sequence of operations - do not require a conscious

control

o If one of these actions is poorly performed or the sequence is applied in an

unusual order.

• Errors based on rules: The selection of actions in a situation often depends on the implementation of a set of rules of the type IF(condition) THEN (action)

o The activation of the right rules depends on the interpretation of the

situational conditions

o If a situation is misinterpreted the retrieved rule will be inappropriate as well

Situation awareness and attention

• The processes of conscious perception and understanding of the

situation

• complex tasks such as flying an airplane, - necessary to process

huge amount of data on what is happening in the cabin , in the air

outside the plane, and even at the airport and the control tower.

• information - attentively handled, retained, interpreted and used

to make necessary decisions for the airplane to fly properly and

landed safely

Situational awareness includes three levels of

information processing:

(1) perception of the elements of the environment;

(2) understanding the current situation;

(3) predicting(projecting) the situation’s future

development

• Instability of human performance related to the automation of work processes

• High degree of automation, human operator is out of loop of controlling processes - operators are less well practiced in their abilities to take over the process when an automatic unit fails

• Manual and cognitive skills decline due to the absence of active participation in the process

• Difficult with progressing automation to gain access to knowledge

about the system behavior

Mental Models:

• When interacting with a system, people normally have some knowledge of its structure and functioning

• Taking into account the peculiarities of users’ mental models in the design of artefacts is crucial for an efficient interaction

• Therefore, the investigation of mental models is one of the central themes in cognitive ergonomics (Canas, Antolí and Quesada, 2001)

• A model that is constructed and simulated

within a conscious mind

• Mental models contain knowledge and help

us create new knowledge

Learning with and about artefacts

• After designing a new artefact users must learn to interact with it

• New artefacts - more complex requiring - more complex cognitive abilities

• Technological progress is so fast that nobody can expect to learn to interact with an artefact and continue using it for long time

• eg:, earlier - typewriters, and now - computers and text editing programs that have completely changed

• So topic of learning is as important as the topic of design itself

Safe User Centered Design In Industry

Designing a sign so that the majority of people will understand and act in the intended manner

Cognitive Task Analysis (CTA)• Provides a formal set of methods for identifying the mental

activities required by a task and an artifact, such as a desktop computer system

• Identify bottlenecks and critical paths - opportunities for

improvement or risks (such as human error) that merit

changes in training or system behavior.• Both people and artefacts are jointly regarded as agents .

The focus is on the transfer and processing of information

within and between agents such as the military, air traffic

control, aircraft cabins or navigation systems for large ships.

• Cognitive Task Analysis may include:

cognitive interviewing analysis of verbal protocols multi-dimensional scaling computer simulations of human performance

(cognitive simulations) human error analysis

• Understanding of the demands of the work situation, user strategies in performing cognitive tasks and limitations in human cognition.

• In some cases, the artifacts or tools used - impose their own constraints and limitations (e.g., navigating through a large number of GUI screens)

• modern artifacts (e.g., control panels, software, expert systems) are becoming increasingly sophisticated

MAN MACHINE SYSTEMS:

• Man holds key position(decisions)

• Recording display – information about the progress of production -eg. fluctuations of temp. or pressure throughout a chemical production

• Operator receives this inform visually (perception)

• Must understand and assess correctly (Interpretation)

• On d strength of his interpretation & in d light of his previous knowledge- takes a decision

• Communicate this decision to machine by using controls

• Control display tells operator the result of his actions eg how much water is mixed with the reagents

• Machine then carries out the production process as programmed

• Man & machine - combine to form a very productive system, - their respective qualities are sensibly used.

• Proper communication. • Operator tells machine, what to do, using controls &

input devices and he is told what to do and what not to do by display’s, sign’s, signals and other information

• Extent to which messages from a machine are correctly communicated - very imp - large impact on product quality & usability

When more elaborate controls & higher output (like in development of electronics)

Consequently -high need for accurate interpretation of the information displayed

Operators task - more delicate and more demanding

eg: In an aircraft d speed of pilot’s reaction can be vital In chemical process alertness & correct decision taking

may alone avert the catastrophe

• So man machine system needs to be ergonomically

sound

• The points of interchange from man to machine &

from machine to man interfaces- very imp

• Ergonomic interfaces of man machine system:

Perception of all information on display

Manually operating the controls

COGNITIVE CONTROLS :• Big machines in industry, agriculture, transport - control panel - many

similar controls & it is important to be able to pull the right lever or turn the right knob, sometimes even without seeing it.

• Therefore controls that might be mistaken for each other should be so designed- identified without difficulty –can be assured by:

• Proper arrangement- like in sequence of operation or difference between vertical & horizontal movements

• Structure & material- like knobs of different shapes & size, difference in surface texture(smooth, ridged etc)-helpful if control has to be handled unseen

• Color & labeling • Controls - certain minimum distance apart to be operated freely &

correctly• Resistance - some amount of resistance to operation- less likely to be

triggered off by a slight movement.

Cognitive Modeling

• Produce a computational model for how people perform tasks

and solve problems, based on psychological principles

• These models may be outlines of tasks written on paper or

computer programs which enable us to predict

the time it takes for people to perform tasks,

the kinds of errors they make,

the decisions they make or

what buttons and menu items they choose

Model human processor

Predetermined time system which contains the time predictions

for very basic elemental information processing tasks.

• This model predicts median performance times & expected time

ranges for simple cognitive tasks

• Assumes that the task involves a series of sensory & information

processing steps followed by a motor activity

• Each step requires time to be performed

• Total task time is the sum of times required for separate activities

• It consists of 3 different processors :1)Perceptual processor: places visual or auditory image

into a short term sensory store & the corresponding code into working memory

Median time= 100ms2)Cognitive processor: checks for matching between items

in working memory, retrieves information from memory, make decisions & select a response

Median time=70ms3)Motor processor: executes the physical act decided uponMedian time=70ms